One of the reasons for noise and vibration in rotary electric machines results from dynamic forces being transmitted from the stator to the casing in which it is mounted. Such dynamic forces, in particular of electromagnetic origin, appear as vibration starting on the bore radius of the stator. Such vibration is transmitted to the casing via the attachment points at which the stator is attached in the casing. The walls of the casing then act as an amplifier, and considerable acoustic noise and vibration ensues.
In one known configuration, the stator is suspended from metal beams themselves associated with the end plates of the rotary machine. As a result, the vibrating areas of the casing are limited. Unfortunately, that apparatus is limited in power because of the effects of the beams bending.
In another known configuration, the stator is attached to the casing by attachment systems of the metal shoe type. There too, the results as regards reducing acoustic noise and vibration are inadequate because of the isotropic nature of the metal shoes in terms of rigidity.
The inadequate results of those known techniques are due to the need to have considerable stiffness between the stator and the casing. It is necessary to have considerable rigidity between the stator and its supporting structure (the casing) in order to take up the static forces of the rotary electric machine so as to prevent major static eccentricity between the rotor and the stator. Such eccentricity increases the amplitudes of the dynamic and static excitation forces. Major eccentricity can give rise both to an increase in the amplitude of the vibration and to the stator sticking to the rotor.
Unfortunately, such necessarily high stiffness constitutes an excellent pathway to the casing for the noise-generating vibration.